<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
		<title>案例3.2</title>
		<style>
			*{
				margin: 0;
				padding: 0;
			}
			.demo{
				display: flex;
				align-items: center;
				flex-wrap: wrap;
			}
			.demo div{
				box-sizing: border-box;
				width: 33.33%;
				height: 50px;
				border: 1px solid #000;
			}
		</style>
	</head>
	<body>
		<div class="demo">
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
		</div>
	</body>
</html>